Aberrant Right Subclavian Artery-To Test or Not to Test, That Is the Question

Objectives This study aimed to determine if isolated fetal aberrant right subclavian artery (ARSA) is associated with an increased risk of chromosomal abnormalities and to see whether or not invasive testing should be considered.Methods We conducted a retrospective study from January 2017 to December 2021. All prenatally diagnosed cases of ARSA were reviewed and their clinical data were collected. Amniocentesis was advised after genetic counseling in every case of ARSA.Results One hundred and thirteen patients of ARSA were diagnosed at 21.2 +/- 2.4 weeks of gestational age. Eighty-eight fetuses had isolated ARSA. Eighty-three patients underwent amniocentesis. Of those, six had Down syndrome and one had Turner syndrome. Four fetuses with genetic abnormalities had no other ultrasound findings; however, the association of isolated ARSA with chromosomal abnormalities was not statistically significant ( p -value = 0.998). Ten patients underwent termination of pregnancy including seven with chromosomal abnormalities and three fetuses with other structural anomalies. The mean age of postnatal follow-up was 2.2 years. Mild respiratory distress was seen in one fetus. No neonatal intensive care unit admissions were present.Conclusion Isolated ARSA by itself does not significantly increase the risk of associated chromosomal abnormalities. The detection of fetal ARSA, however, mandates a detailed fetal ultrasound. Invasive testing can be deferred in cases of isolated ARSA. Larger prospective studies are required to see the role of cell-free DNA as an optimal alternative option.